When `40mL` of a `0.1 M` weak base, `BOH` is titrated with `0.01M HCl`, the `pH` of the solution at the end point is `5.5`. What will be the `pH` if `10mL` of `0.10M NaOH` is added to the resulting solution ?

Explanation

To solve the problem step by step, we will follow the titration process and the subsequent addition of NaOH to the resulting solution.

### Step 1: Calculate the moles of the weak base (BOH) and HCl at the endpoint.
- Volume of BOH = 40 mL = 0.040 L
- Molarity of BOH = 0.1 M
- Moles of BOH = Volume × Molarity = 0.040 L × 0.1 mol/L = 0.004 moles (or 4 millimoles)

At the endpoint of the titration, the moles of HCl will equal the moles of BOH:
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